Hydrogenative conversion of hydrocarbons



United States Patent O HYDROGENAT IV E CONVERSION OF HYDROCARBONS GeorgeAlexander Mills, Swarthmore, Pa., assigner to Houdry ProcessCorporation, Wilmington, Del., a corporation of Delaware t ApplicationNovember 20, 1951, Serial No. 257,361

9 Claims. (Cl. 208--146) This invention relates to the conversion ofhydrocarbon materials in the presence of hydrogen, and is particularlydirected to conversion of dierent types of hydrocarbon materialssimultaneously within a common system under conditions of heat balance,such that the sensible heat released during an eXothermic reaction stageapplied to one type of hydrocarbon material in the system isbeneficially utilized to supply the heat requirements for an endothermicoperation applied to another type of hydrocarbon material undergoingconversion in the system.

It is well-known that heavier hydrocarbons and hydrocarbonaceousmaterials such as petroleum oils, shale oils, coils, tars and the likecan be converted at elevated temperatures and pressures in the presenceof hydrogen to obtain,` by a process generally known as destructivehydrogenation, yields of lighter boiling hydrocarbons such as those inthe gasoline range. Another operation well-known in industry is thereforming of lighter hydrocarbons such as light and heavy naphthas alsoat elevated temperatures and pressures in the presence of hydrogen toobtain thereby modified hydrocarbon materials having certain desirableattributes such as higher octane numbers, an increased spread through adesired boiling range and other improvements. These two types ofconversion are operated at relatively divergent conditions of pressure;the destructive hydrogenation step is high- 1y exothermic While thereforming step is endothermic, thus requiring considerable differencesin operating conditions control and procedure. Another general dierenceapparent with these two types of operation is that the reformingoperation is generally performed without the formation in anyappreciable amounts of hydrocarbonaceous deposit or colte, whereasdestructive hydrogeneration, or hydrogenative cracking or hydroerackingas it may be termed, generally results in the formation of appreciableamounts of coke. Thus, the reforming type of oper-ation, providedsufficient heat is supplied in controlled amounts, can be continuedalmost indefinitely, at least in so far as the presence of cokeinhibiting or stopping the reaction is concerned; Whereas with thehydrogenative cracking operation arrangements must be made for theperiodic removal of such coke deposit as may be formed in the reactor inor on any surface of such contact mass as may be used in the operation.

It is an object of this invention to provide a system for` thesimultaneous conversion by hydrocracking and by reforming of theappropriate types of charge stocks. It `is a further object of thisinvention to provide a system in which the eXotherrnic heat of thehydrocracking reaction is efficiently utilized subsequently by thereforming conversion operation while simultaneously utilizing theAendothermic phenomenon of the reforming `conversion operation tosubsequently control within ,reasonable limits the exothermic heat ofthe cracking operation. Another object of the invention is to operatethis system in such manner that the periodic removal of rificehydrocarbonaceous deposit resulting in the hydrocracking operation iseiciently and effectively performed during the reforming operationwithout any appreciable interruption thereto. Another object is toprovide means and apparatus whereby the system may be operatedefiiciently and economically while obtaining these and other desiredresults. In accordance with the invention a heavy hydrocarbon charge,which may be a topped or reduced crude petroleum oil, is contacted withcatalyst having hydrogen lactivating properties at elevated pressure andunder conditions of temperature to promote hydrogenative cracking of thecharge. The reaction being strongly exothermic, sensible heat is storedin the catalyst and the temperature of the catalyst (and of theenvironment) is accordingly raised, while a small but significantquantity of hydrocarbonaceous deposit is formed in the catalyst. After apredetermined period of such operation, the ow of the heavy charge isdiscontinued and after suitable adjustment to lower pressure of thereaction zone, the same catalyst is now contacted with a hydrocarboncharge to be reformed. One of the principal reactions reactions takingplace lin this latter step is dehydrogenation, which is endothermic, andthe heat stored in the catalyst during the previous eXothermic step isbeneficially utilized. During the reforming operation, the temperatureof the catalyst and its environment is thus reduced to a suitable leveland the hydrocarbonaceous deposit therein is removed to a majorextent-seemingly as a result of concomitant hydrogenation thereof takingplace-preparing the catalyst and the reaction zone, after a Xed periodof operation under reforming conditions, to be used again forhydrocracking of heavy charge, pressure being again adjusted.

In the preferred operation, a system of reaction vessels is provided sothat the process can be carried out continuously, one or more Vessels inthe system being switched periodically, so that each vessel operatesalternately in hydrocracking and in hydroforming, while the severalcharges are thus being supplied and treated substantially continuously,In addition to the advantages of temperature control in the process andretarding or preventing the accumulation of hydrocarbonaceous deposit,the reforming and hydrocracking are mutually interrelated in that thehydrogen produced during the reforming step is needed and can beutilized in hydrocracking, while the products from hydrocracking includesaturated materials which can be reformed to more valuable products andconstitute a desirable charge to the reforming operation.

A more complete understanding of the invention and an appreciation ofother advantages thereof will be had from the detailed description whichfollows read in connection with the accompanyinng drawing illustrating aow diagram of a typical arrangement for the practlce thereof.

With reference to the drawing the general flow pattern of the system inaccordance with the preferred embodiment can be followed readily. Theoperation of the system thus illustrated `is as follows: higher boilinghydrocarbon charge is admitted through line 11 to reactor A forhydrogenative conversion at hydrocracking conditions and in contact witha suitable catalyst having the desired activity for the hydrocracking(as well as for reforming) reaction; such catalysts include, forexample, platinum supported on silica-alumina, nickel supported onsilicaalumina, platinum supported on alumina, molybdenaortungsten-containing catalysts or other catalysts having hydrogenactivating properties. The conditions used for hy- `drocracking arethose familiar` for this operation and include liquid hourly spacevelocity in the range of 0.5 to 4.0 volumes of oil per volume ofcatalyst and temperatures of 900l050 F., although temperatures above andIbelow this range are also suitable and dependent to considerable extenton the extent of reaction desired and the type of charge stock admitted`for conversion;v hydrogen to oil ratios inthe order of 3/1 to 10/1 on amolar basis and pressures generally in excess of 75 atmospheres,although lower pressures can be employed; pressure of 100 atmospheres`or more is preferred.

The hydrogenative cracking reaction is continued for a predeterminedperiod based on the heat balance of the system, which in a typicaloperation will be approximately one hour, during which time thetemperature rise within the reactor may -be approximately 70 with aconcomitant deposition on the contact mass of an appreciable amount ofhydrocarbo-naceous material. Simultaneously and concomitantly, reactor Bcontaining the same type and amount of catalyst as reactor A isfoperating at reforming conditions with a naphtha charge introducedthrough line 21. The temperatures of the several reactions should not beallowed tofluctuate more than 100 during the operating periods whichhave been described as. of approximately one hours duration but whichmay be longer or shorter to meet operating requirements.

The conditions of reforming include temperatures of approximately900-1050" F., pressures less than 100 atmospheres and preferably lessthan 50` atmospheres, a liquid hourly space rate in the range of l-6 andhydrogen to oil ratios of l/ l to 10/1. The catalyst type previouslymentioned is used for reforming also. in order to achieve the desiredheat balanced arrangement in the several cases, it isv necessary tooperate the reforming unit over approximately the same temperature rangeemployed for hydrocracking, except that while during the hydrocrackingthe temperature swing is from the lower to the higher value in*v thisrange, during reforming the opposite takes place. Iln the embodimentunder discussion, for instance, if approximately 3,000 bbls. of atypical charge per on-stream `day are introduced to the hydrocrackingstep, the heat evolved thereby is approximately equal to the heatrequirement in the reforming of approximately 3 times as much of atypical naphtha stock, or approximately 9,000 bbls. per oli-stream day.ln view of these charge stock requirements, it is apparent that theproducts of hydrocracking boiling in the described naphtha range wouldbe insufficient for Ifull charge to the reforming operation; therefore,such charge will preferably comprise in addition material of suitableboiling range, such as naphtha, gasoline, as from catalytic crack-ingand'/ or thermal cracking or other suitable sources. The reforming step,in the describedv relation, is likewise continued for a period of ap'-proximately l hour with a concomitantv temperature drop of approximately70.

A typical cyclic operation for the practice of this i-nvention may be ofthe nature `described below.

Considering rst reactor A operating at hydro-cracking conditions, thecharge stock from a suitable source, not shown, and which may besupplemented by recycle stock, is introduced through suitably valvedline 11 for conversion. The proper amount of hydrogen, which may berelatively pure hydrogen Ifrom a suitable outside source, not shown, ora mixture of pure hydrogen and recycle gas predominately hydrogen, or arecycle gas such as from the products of dehydrogenation andpredominately hydrogen is admitted through line 12 and control valve 12ato, reactor A. Products of the hydrocracking reaction are removed fromreactor A through line 13 and passing through.V control valve 13a enterthe fractionator 114i for fractional distillation into suitablefractions.. In the illustrated embodiment the fractions are the` lightgases, i.e., Crhydrocarbons andv lighter; a 50`l80 F.. light gasolinecut removed through line 15;` a 180-3 80 F; heavy gasoline cut removedthrough line 16; anda ybottoms fraction boilingabove 380` F; and removedthroughV line 17. rlhe light gases, removed through line 18, may be sentto any desired usagek while the light gasoline fractionl is 4 blendedwith other materials to form part of the final gasoline product, theheavy gasoline is sent as part of the charge to reforming, and thebottoms fraction is recycled to the hydrocracking reaction for 4furtherconversion to lighter products.

Considering next the reforming operation occurring in reactor Bsimultaneously with the hydrocracking reaction in reactor A, the napthacharge, from a suitable source not shown, supplemented by the heavygasoline fraction from fractionator 14 is introduced through line 21 andvalve 2lb to reactor B. The proper amount of hydrogen-containing gas isadmitted to reactor B through line 12 and control valve 12b. Products ofreforming are removed from reactor B through line 22 and passing throughcontrol valve 22a enter separator 23 for fractionation into a light gasfraction removed through line 24 and a reformed gasoline removed throughline 25 to form at least a portion of the product gasoline.

After the system has operated for a suitable time period in which thetemperature in the reaction Zone of reactor A has increased as a resultof the exothermic nature of the hydrocracking reactionk from aninitially relatively low temperature to a temperature approximatelyequivalent to the temperature initially prevailing in reactor B, and thetemperature in the reaction zone of reactor B has decreasedl as a resultof the endothermic nature of the reforming reaction from an initiallyrelatively high temperature to a temperature approximately equivalent tothe temperature initially prevailing in reactor A, the operation isadjusted `to utilize the existing temperature conditions and to obtain asubstantial reduction. of such coke deposit as formed on the catalystduring the hydrocracki'ng reaction. The adjustment entails switching thereactions so that reactor A previously operating at hydrocrackingconditions subsequently operates at reforming conditions and reactor Bpreviously operating at reforming conditions operates at hydrocrackingconditions. The charge stocks are likewise shifted to the properreactors. In the illustrated embodiment the heavy stock charge isdiscontinued to reactor A by the closing of valve 11a and the naphthacharge to reactor B is discontinued by the closing of valve 2lb.Reactors A and B may be flushed for a short period by the hydrogenadmitted through line l2 and the pressure conditions of reactor A areadjusted to that of reforming, i.e., lower pressure, and the pressure inreactor B isV raised to` the proper pressure for hydrocracking. Theclosing of valve 13a and the opening of valve 13b provides for thetransfer of the effluent from reactor A to separator 23 instead of tofractionator 14 while the closing of valve 22a and the opening of valve221) provides for the transfer ofthe effluent from reactor Btofractionator 114 instead of to separator 23. Reactor A is placed onstream by the admission of the naphtha charge through line 21 by theopening of valve 21a and reactor B is placed on stream by the admissionof the heavy stock charge through line 11 by the opening of valve 11bthus providing substantially continuous operation with` only arelatively minor interruptionof the flow of materials, and' the periodicalternation of these switching ,adjustments provides for cyclicoperation substantially continuously.

In reactor A the higher temperatures andV the excess hydrogen inaddition to the reforming of the charge stock passing therethroughremoves by hydrogenation the hydrocarbonaceous, or coke, depositremaining in Ithe reactor from the preceding hydrocracking step. Thetemperature effects of each of the several reactions, again continuedfor approximately an hour, are once again equal but opposite to thatoccurring in the reactors during the preceding on-stream period and thusthe reactors are returned again to the temperature level at theexpiration ofthe ori-stream time where, by suitable readjustment of thecharge stocks and the related conditions, hydrocracking is againresumedin reactor A and reforming is resumed in reactor B.

As an aid in obtaining this temperature balance, there may be admixedwith the catalyst a contact mass of suitable high heat capacity materialhaving the sole purpose of acting as a heat storage or delivery mediumwhereby the temperature increases are stored therein during theexothermic hydrocracking operation to be subsequently delivered duringthe endothermic reforming step. Suitable heat capacity materials includealundum, corhart, fused alumina, quartz, and other materialssubstantially inert and nonreactive at the operating conditions. =Heatstorage is also provided in part by the reactor walls and relatedequipment adjacent the reaction zone. In fact, reactors suitable for thehigh temperatures and high pressures involved are so constructed that anappreciable heat storage capacity is provided by the vessels andinternals thereof.

As an aid in determining, but not as limiting, the requirements relativeto heat input and the balance of conditions necessary in the reformingoperation it can be stated generally that the heat capacities of thereactants are roughly: hydrogen is equal to 3.6 calor-ics per gram perdegree C.; the oil is equal to 0.6 calorie per gram per degree C.; andthe catalyst of the types described (exelusive of the heat capacitymaterial) is equal lto about 0.25 calorie per gram per degree C., all at900 F. basis. On the basis of charging 2 kgs. of oil per kg. of catalystper hour at a to 1 hydrogen to oil mol ratio, the heat capacity of theoil is 1200 calories per degree, that of the hydrogen is 1800 caloriesper degree and that of the catalyst 250 calories per degree; the heat ofreforming is approximately 110,000 calories per kg. The exothermic heatof the hydrocracking reaction as previously mentioned is approximatelythree times that of but opposite to the endothermic heat of reformingthus indicating the necessity of operating hydrocracking withapproximately one-third the throughput of the charge stock as that ofthe charge to reforming; however, this heat relationtis not to beconstrued as absolute inasmuch as differences in charge stocks,particularly for hydrocracking, may alter this such that the exothermicheat may be considerably less than three times that of the endothermicreaction and thus necessitate change in the respective charge rates.

Example A practical example of an operation in accordance `with theforegoing description is as follows. The reforming of hydrocrackednaphtha in the reforming section of such system was effected atconditions of 950 F., 600 p.s.i., liquid hourly space velocity of 4 andhydrogen to oil ratio of 4 and using a catalyst of platinum (01.5% wt.)supported on alumina. The naphtha charged to this operation had cutpoints of 180 and 380 F. and had an octane rating of 60.1 F-l clear.There was obtained in the products 92 Wt. percent C5+, 5.7 wt. percentC4s and 1.6 wt. percent of dry gas. The liquid product had an octanerating of 86.2 F-l clear and 97.1 F-l'+3 ccs. TEL. The blending of theinitial to 180 F. fraction of hydrocracked product with this reformedfraction gave a gasoline material having an F-l clear rating of 83.6 andan F-1+3 ccs. TEL of 95.2 at 7 lbs. RVP.

Simultaneously in the hydrocracking section utilizing the same type ofcatalyst, an East Texas gas oil fraction comprising a 56-77% cut andrecycle heavy naptha were charged at hydrocracking conditions includingtemperature of approximately 900 F., 1500#'/sq. in. pressure, hydrogento oil ratio of 6 and liquid hourly space velocity of 2 (includingrecycle heavy naphta). The yields from such hydrocracking based on theamount of fresh feed to the reactor were 99.1 volume percent of (35+gasoline, 17.8 volume percent of C4s and 8.3 wt. percent of dly gas. Thegasoline was subsequently fractionated into three cuts; namely, initialto 180 F. (30%), ISO-380 F. (51.3%) and 380 F. bottoms. The middle cutsupplemented with similar material was the charge to the reforming andthe light cut was used to blend with reformed products as describedabove. The heavy cut was recycled to hydrocracking. The hydrocrackingoperation was accompanied by the deposition on the catalyst ofapproximately 1.2 grams per liter of hydrocarbonaceous material.

At the end of approximately one hour the charge stock to each of thecases was discontinued and by appropriate manipulation of the feed lineswas switched to enter the opposite cases with the conditionsof thesecases adjusted accordingly in such manner that the case formerlyoperating at reforming conditions now operated at hydrocrackingconditions and the case used for hydrocracking now operated forreforming. The products from each of these reactions were approximatelythe same as those obtained in the first hour of operation and the cokedeposit on the catalyst retained after the original hydrocrackingoperation Was reduced during the onstream reforming period from 1.2grams per liter to approximately 0.3 gram per liter. During the courseof the reaction in the second hour the temperature in the reaction zoneused for hydrocracking rose from about 900 to about 950l F. and thetemperature in the reaction zone used for reforming dropped from about950 to about 900 F. Alternating or switching these reactionsperiodically after time periods of approximately one hour on-streampermitted continuous operation at relatively uniform temperatureconditions and under circumstances at which at no time did the cokedeposit on the catalyst exceed 1.5 grams per liter while maintaining anaverage concentration on the catalyst of less than 0.5-0.7 gram perliter; thus maintaining a system in which temperature balance existedbetween the two reactions and the coke product of the hydrocrackingoperation was held in control at relatively low levels by hydrogenativeremoval during the reforming operation.

The foregoing embodiments are presented as illustrative only and theinvention is` subject only to such limitations of scope and variationsas may appear in the appended claims.

I claim as my invention:

l. The method of hydrogenative conversion of hydrocarbons to moredesirable products which comprises effecting hydrogenative conversion ofone kind of hydrocarbons in one reaction zone containing catalyst havinghydrogen activating properties at exothermic conditions andsimultaneously in at least one other separate reaction zone containingcatalyst having hydrogen activating properties in the same systemeffecting hydrogenative conversion of a different kind of hydrocarbonsat endothermic conditions differing as to at least one of the variablesselected from pressure, space rate, temperature and reactant ratio,switching charges and conditions for each of said reaction zones andthereafter effecting in said second reaction zone the reactionpreviously conducted in the 4first reaction zone and simultaneouslyeffecting in said first reaction zone the reaction previously conductedin the second reaction zone, thereby utilizing and controlling thetemperature effects of the immediately preceding reaction period, andcontinuing the cycle operation periodically to utilize and control thetemperatures of the several reactions.

2. The process for the hydrocracking `of high boiling hydrocarbons togood yields of gasoline range materials and for the reforming ofnaphthas to improved products simultaneously and in cycle in the samesystem but in separate reaction zones at different reaction conditionscomprising, owing high boiling hydrocarbon change to a first reactionzone containing `catalyst having hydrogen activating properties forconversion at hydrocracking conditions, flowing naphtha charge to asecond reaction zone containing catalyst having hydrogen activatingproperties for conversion at reforming conditions at a pressure lowerthan employed in the hydrocracking conditions, continuing such reactionssimultaneously for a time period of such duration that the temperaturerise from the exothermic hydrocracking reaction of the high boilingfraction in said first reaction zone approaches the temperatureinitially obtaining in said second reaction zone while the temperaturedecrease from the endothermic reforming reaction of naphtha in saidsecond reaction zone approaches the temperature initially obtaining in.said rst reaction zone, switching charges and conditions for each ofsaid reaction zones and thereafter effecting hydrocracking -in saidsecond reaction zone simultaneously with the reforming in said firstreaction zone at a pressure lower than employed in the hydrocrackingzone, thereby utilizing and controlling the temperature effects of theimmediately preceding reaction period, and continuing the cycleoperation periodically to utilize and control the temperatures of theseveral reactions.

3. The process of claim 2 in which said catalyst is platinum supportedon silica-alumina.

4. The process of claim 2 in which the temperature rise duringhydrocracking is less than 100 F. and the Vtemperature decrease duringreforming is less than 5. The process of claim 2 in which the initialtemperature of hydrocracking is about 900 F. and the initial temperatureof reforming is about 970 F.

6, The process for the hydrocracking of high boiling hydrocarbons togood yields of lower boiling hydrocarbons and for the reforming ofnaphthas to improved products including high octane gasoline in heatbalanced relationship within the same system but in separate reactionzones by continuous cycle comprising, introducing high boilinghydrocarbon charge to the system in a first reaction zone for conversionat hydrocracking conditions including temperatures of 900-1050 F.,pressure in excess of 75 atmospheres, added hydrogen in mol ratio to theoil charge of 3 to 10 to 1 and liquid hourly space velocity in the rangeof 0.5 to 4.0, and in the presence of a platinum catalyst supported onsilica-alumina, said catalyst having hydrocracking and reformingactivity, effecting hydrocracking with attendant temperature elevationfrom about 900 F. to less than 1000 F. and deposition of inactivatingamounts of coke on the catalyst, terminating said hydrocracking in saidlrst reaction zone by discontinuing the introduction of high boilinghydrocarbon 4charge to said first reaction zone; introducing naphthacharge to the system to a second reaction zone for conversion atreforming conditions including temperature of 900-1050 F., pressurebelow 75 atmospheres, added hydrogen in mol ratio to the naphtha chargeof l to l to 1, and liquid hourly space velocity in the range of 1-6,and in the presence of a platinum catalyst supported on silica-alumina,said catalyst having hydrocracking and reforming activity, effectingreforming with attendant temperature decrease from about 950 F. to aVtemperature greater than 850 F., terminating s aid reforming in saidsecond reaction zone lby discontinuing naphtha charge to said secondreaction zone simultaneously with said termination of said hydrocrackingin said rst reaction zone; introducing said high boiling hydrocarboncharge to said second reaction zone having lower temperature andeffecting hydrocracking therein similar to that previously effected insaid ii-rst'reaction zone; introducing said naphtha charge Ato saidiirst reaction zone having higher temperature and eecting reformingtherein similar to that previously effected in said second reaction zoneand simultaneously removing substantial amounts of said coke from Saidcatalyst to effeet substantial reactivation thereof; and periodicallyalternating said hydrocracking and said reforming reactions in `saidiirst and said second reaction zones to maintain heat balance andcatalyst reactivation.

7. The process of claim 6 in which the initial temperature ofhydrocracking is about 900 F. and the initial temperature of reformingis about 950 F.

8. The process for the production of good yields of high octane gasolineby hydrocracking high boiling hydrocarbons and reforming naphthassimultaneously and in cycle in the same system but in separate reactionzones comprising, subjecting high boiling hydrocarbon charge stock tohydrocracking in a iirst reaction zone containing catalystl havinghydrogen activating properties, simultaneously subjecting naphtha chargestock to reforming in a second reaction zone containing catalyst havinghydrogen activating properties; passing products of said hydrocrackingto fractionation into at least three fractions comprising a lightgasoline, a heavy gasoline and a higher boiling fraction, recycling saidhigher boiling fraction as part of said charge to said hydrocracking,passing said heavy gasoline as part of said naphtha charge to saidreforming, and recovering said light gasoline as part of said highoctane gasoline; passing products of said reforming to separation into alight gas fraction and a gasoline fraction, recovering said gasolinefraction as part of said high octane gasoline, recycling said light gasfraction to saidV hydrocracking and said reforming as at least a portionof the hydrogen-containing gas supplied thereto; and periodicallyalternating said hydrocracking and said reforming between said firstreaction zone and said second reaction zone when the temperature of saidhydrocracking reaches the temperature initially prevailing for saidreforming and the temperature of said reforming reaches the temperatureinitially prevailing for said hydrocracking.

9. The process of claim 8 in which said high octane gasoline product isa blend of reformate from said reforming and of light gasoline fractionof the product of said hydrocracking.

References Cited in the file of this patent .UNITED STATES PATENTSHaensel et al. Nov. 17, 1953 UNITED STATES PATENT OFFICE CERTIFICATE OECORRECTION e one .13@ September l, 1959 George Alexender Mille It ishereby certified that error appears in the printed specification of' theabove numbered patent requiring correction and that the said LettersPatent should reedy as corrected below.

Column l, line 28, for "coils" reed me @nele me; eelulnn 2, line 22,Strike out "reeetione, second occurrence; @elw-rm 59 line 6'?, for"nephte" reed me nepfithe ne; eolumn '7, line 5, eiter "of" insert m theSigned, end sealed this 9th dey et February 196m (SEEE) Attest:

KARL Ii., AXLINE ROBERT C. WATSON Commissioner of Patents AttestingOfficer

1. THE METHOD OF HYDROGENATIVE CONVERSION OF HYDROCARBONS TO MOREDESIRABLE PRODUCTS WHICH COMPRISES EFFECTING HYDROGENATIVE CONVERSION OFONE KIND OF HYDROCARBONS IN ONE REACTION ZONE CONTAINING CATALYST HAVINGHYDROGEN ACTIVATING PROPERTIES AT EXOTHERMIC CONDITIONS ANDSIMULTANEOUSLY IN AT LEAST ONE OTHER SEPARATE REACTION ZONE CONTININGCATALYST HAVING HYDROGEN ACTIVATING PROPERTIES IN ATHE SAME SYSTEMEFFECTING HYDROGENATIVE CONVERSION OF A DIFFERENT KIND OF HYDROCARBONSAT ENDOTHERMIC CONDITIONS DIFFERING AS TO AT LEAST ONE OF THE VARIABLESSELECTED FROM PRESSURE, SPACE RATE, TEMPERATUARE AND REACTANT RATIO,SWITCHING CHARGES AND CONDITIONS FOR EACH OF SAID REACTION ZONES ANDTHEREAFTER EFFECTING IN SAID SECOND REACTION ZONE THE REACTIONPREVIOUSLY CONDUCTED IN THE FIRST REACTION ZONE AND SIMULTANEOUSLYEFFECTING IN SAID FIRST REACTION ZONE THE REACTION PREVIOUSLY CONDUCTEDIN THE SECOND REACTION ZONE, THEREBY UTILIZIANG AND CONTROLLING THETEMPERATURE EFFECTS OF THE IMMEDIATELY PRECEDING REACTION PERIOD, ANDCONTINUING THE CYCLE OPERATION PERIODICALLY TO UTILIZE AND CONTROL THETEMPERATURES OF THE SEVERAL REACTIONS.